The fluidization quality in a reactor resides in obtaining a distribution which is as perfect as possible of the fluidization liquid at the base of the reactor, while avoiding the formation of dead zones or preferential passages.
If these conditions are easy to meet for apparatus of small surface area (for example less than 1 sq. meter) at acceptable costs, the same does not apply to apparatus of a large surface area and when the liquid contains materials in suspension which might block the distribution system.
In the case of filters, one often uses perforated floors which allow fluidizing the filtration material, with a view for example to sort it again after washing.
The device which is the most often used is a distribution system including a general collector in which are fixed branches including in turn distribution openings possibly fitted out with strainers. These devices can be immersed inside a layer of a non fluidized material in order to improve the distribution and/or prevent, when at rest, the solids to be fluidized from coming in contact with the distribution openings.
Such techniques are used for example in ion exchange reactors, or in fluidized bed methanization reactors.
A device of the type previously described but in which the branches extend through the reactor walls has also been proposed, and in order to suppress at best the dead zones, there is provided a filling body between each branch.
All these devices include many points of distribution per unit of surface and have the disadvantage of presenting, inside the reactor on a same branch, several points of distribution, the clogging-up state of which is difficult to control, either in operation or after an incident which might have caused a penetration of the material to be fluidized in the branches.
This concept might cause a degradation of the fluidization which can be remedied only after a delicate and costly discharge of the material to be fluidized.
On the other hand, it is not always possible to obtain with such devices a good compromise between fluidization flow rate, the number of points of distribution per unit of surface, the distribution energy and the diameter of the distribution opening, as a function of the various applications.